Corrosion of steel reinforcements in concrete is much accelerated by the presence of chloride ions. This is particularly a problem where salt (sodium chloride) is used for de-icing of concrete road surfaces, which may percolate through the reinforced concrete.
It is well known to apply an electric current between the (cathodic) steel reinforcements and a closely adjacent anode device so as to encourage chloride ions to migrate away from the steel reinforcement.
It is required that the anode device should be made from a material which has adequate electrical properties, which is sufficiently durable to withstand long use in possibly adverse conditions, and which is suitable, in terms of cost and convenience of installation, for widespread use over large concrete areas.
One known material is a settable carbon gel injected into drilled holes with inserted primary anodes.
Another known material is a carbon paint applied as a surface coating.
A further known material is a titanium substrate which has a conductive mixed metal oxide coating, formed into a suitable shaped structure, such as a mesh, a ribbon or tubular structure.
A further known material is a conductive ceramic material formed as a tubular structure with an inserted electrical contact.
These known materials can have drawbacks in terms of operational efficiency and/or durability and/or convenience of manufacture or installation. In particular, there is the problem that they require introduction of additional structures into the structural body to be protected which may be inconvenient and could even impair structural integrity of the body.